LONDON -- Calls for the universal criminalisation of doping violations in sport are getting louder after two of the world's greatest marathon runners added their voices to that of Paula Radcliffe.

Double winner of the London Marathon and New York's reigning champion after three consecutive victories, Mary Keitany, and two-time Chicago Marathon champion Florence Kiplagat, spoke out on Wednesday.

They called for tougher sanctions along the lines of those seen in countries such as Italy, Austria, Germany and Australia, at the end of what were depressingly familiar scenes for a major athletics event.

The London Marathon launched its elite races by introducing leading runners in a very strong women's field that includes four who have broken the 2 hours 20 minutes mark and four more who have run quicker than 2h 22mins.

While the event organiser stressed all that is great about what is genuinely a moving and incredible day, a doping cloud hung over proceedings.

Last year's winner, Jemima Sumgong, was revealed earlier this month to have tested positive for EPO and is awaiting the results of her B sample; she won't be defending her title and her fellow Kenyans were left to deal with the issue.

Kiplagat told the news conference the initial test result had "embarrassed the sport" and left her "ashamed", and Keitany found it "embarrassing".

Talking to ESPN, they went further. "They are killing the sport for the future," Keitany said of the athletes proven to have doped. "Yes, [doping should be criminalised]. It is not good to come and lie because you will not get anywhere.

"It's like Sumgong: she won last year and is not on the list this year [of London Marathon entrants]. What Paula said should be followed."

But the Kenyans simply sounded tired of seeing the name of their sport and their country besmirched.

Kiplagat finished third in London last year and would have her position upgraded by one place if Sumgong's result was annulled because of a confirmed drug violation. That, at least, she was happy about.

"I agree [dopers should face criminal charges]," the 30-year-old said, blaming financial greed and hangers-on for doping problems. "Once you commit to something and you know these things have been there [on the banned list], why?

"For the love for our country, you have to get banned or what ... I don't know. It's like I came to you and said 'I want this and this'. Am I a doctor? No. So I should be thrown in jail."

Kenya's record in anti-doping has come under intense scrutiny in recent years. More than 40 Kenyan track and field athletes have failed doping tests and been banned since 2011.

The World Anti-Doping Agency (WADA) declared the country non-compliant last year and athletes faced special testing before the Rio Olympics, but required mechanisms have been put in place since to bring local anti-doping mechanisms up to an acceptable standard for the agency.

"When I'm on the [start] line I want to be [known as] clean," said Keitany. "Sometimes people from other countries might not trust in Kenya.

"If I won on Sunday, maybe they would say 'she is the same as the other ones' and I don't want that. I want to run clean and for somebody to think that I'm clean."

Track and field's problems with doping are well known but the latest published statistics from WADA do not show marathon running, particularly, as having more issues than many other sports; the number of confirmed anti-doping rule violations in the 2015 report - five -- was one fewer than in equestrian and one greater than in golf, for example.

There have been high profile cases, of course. Before Sumgong, Rita Jeptoo, a Boston and Chicago champion, tested positive in 2014, and London annulled Liliya Shobukhova's podium places in 2010 and 2011, as well as Inga Abitova's second place in 2010.

WADA has accepted that criminalisation can be effective in catching support personnel that possess or traffic performance enhancing drugs, citing the example of Italy.

But it's position on attempting to create a universal approach has remained the same for some time. It claims the sanctions available to it, with a punishment of up to four years for a first-time offence, and a process that includes the Court of Arbitration for Sport (CAS), is sufficient.

The World Marathon Majors (WMM) -- London, New York, Chicago, Boston, Berlin and Tokyo -- group is working with the IAAF and has invested in additional out-of-competition testing for 150 of the best marathon runners; it has also introduced ways of preventing proven dopers from profiting from its races financially.

The WMM would not disclose the number of athletes tested in the programme it funded two years ago, but Keitany and Kiplagat said they had been subjected to the additional measures.

Some leading sports scientists question whether it is enough, arguing that while this approach is laudable, it only catches the "dopey dopers" and new, more sophisticated methods are required.

Nevertheless, it was one of the WMM-funded tests that brought the positive result for Sumgong and the organisation insisted it is open minded about other approaches.